Factbox: Mars and its missions

Sat Nov 26, 2011 10:04am EST

(Reuters) - Here are some facts about Mars and about missions to the red planet, as United Launch Alliance prepares to send aloft on Saturday an unmanned Atlas 5 rocket carrying NASA's Mars Science Laboratory.

MISSIONS TO MARS:

- One of a pair of Mars rovers that arrived on the planet in January 2004 is still working. Its twin succumbed to the harsh environment in 2010. They returned evidence that Mars was once far wetter and warmer than the dry, cold desert that exists today.

- In November 2008, the Phoenix Mars Lander, which made history by finding definitive proof of water on Mars, lost contact with Earth, effectively ending its more than five-month mission.

- On Saturday, NASA's new Mars Science Laboratory is scheduled to begin a nine-month journey to Mars. Its intended landing site is Gale Crater, which contains a mountain of sediment that is expected to reveal clues about past possible habitats for life.

- The mission is designed to last a full Mars year (687 Earth days) or longer.

- Mars Science Lab, nicknamed Curiosity, is NASA's first astrobiology mission at Mars since the 1970s-era Viking probes.

- NASA is developing a new capsule and heavy-lift rocket intended to send astronauts first to an asteroid and later to Mars.

RUSSIA'S 2011 MISSION:

- Russia, hoping to end a 20-year hiatus from deep space, launched an ambitious three-year mission to scoop a soil sample from the surface of the Martian moon Phobos on November 9 from the Baikonur launch pad on a Zenit-2SB rocket.

- The mission was for Phobos-Grunt to reach Mars in 2012 touch down on the larger of Mars' two tiny moons in 2013, collect a sample from the surface and fly back to Earth in 2014.

- However an engine failed to fire on the probe after it reached Earth's orbit and communication was lost until Thursday, when ESA regained some contact.

KEY FACTS ON MARS AND EARTH:

MARS EARTH

Average Distance from Sun 142 million miles 93 million miles

Average Speed Orbiting Sun 14.5 miles per sec. 18.5 miles/sec.

Diameter 4,220 miles 7,926 miles

Length of Year 687 Earth Days 365.25 Days

Length of Day 24 hrs 37 mins 23 hrs 56 mins.

Temperature Average -81 degrees F 57 degrees F

MARS EXPERIMENT:

- An isolation experiment in Russia simulated a 520-day human mission to Mars. Six volunteers were locked away in windowless cells in June 2010. The $15-million Mars500 experiment, which ended on November 4, was the first full-duration simulation of a human expedition to Mars.

DURING THE MISSION:

- The crew was hermetically isolated.

- After 250 days the crew was divided in half, three sent to a Martian surface simulator and three kept in the 'spacecraft'.

- Crew lived and worked like astronauts on the International Space Station.

- Crewmembers were monitored, and their psychological, medical and physical signs recorded.

2009 MISSION:

- In 2009 four Russians, a Frenchman and a German ended a simulated 105-day space trip in Moscow designed to test how they responded to long-term isolation.

Sources: Reuters/NASA/www.esa.int/

(Reporting by David Cutler, London Editorial Reference Unit; Editing by Irene Klotz and Philip Barbara)

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